He was euthanized Tuesday after veterinarians discovered an inoperable thyroid tumor during a medical exam. Zoo officials said Gus had exhibited unusual feeding behavior and had trouble eating and swallowing his food.

“Gus was an icon at the Central Park Zoo and a great source of joy for our visitors and staff,” said Jim Breheny, executive vice president of the Wildlife Conservation Society, which operates the zoo. “He was an important ambassador for his species, bringing attention to the problems these bears face in the wild due to a changing environment.”

The median life expectancy for a male polar bear in zoos is 20.7 years, according to the Association of Zoos and Aquariums.

Gus was born in 1985 at the Toledo Zoo. He transferred three years later to New York and became an immediate sensation. He soon became known for his obsessive daily swim routine.

About 20 million people have visited Gus at the Central Park Zoo throughout his lifetime, according to zoo officials' estimates.